Regulating means for liquid fuel supply systems of prime movers or other apparatus



March 11, 1952 HARR|$ 2,588,522

REGULATING MEANS FOR LIQUID FUEL SUPPLY SYSTEMS OF PRIME MOVERS OR OTHERAPPARATUS Filed July 15, 1949 TAJia I IJ-S Patented Mar. 11, 1952 UNITEDSTATES REGUI ATINGI; MEANS, FOR. LIQUID FUEL. SjUPPLY'SYSTEMS" F PRIMEMQVERSII 0R. QTH-ER'APPABATUS Thomas-Alfred Harris, Edgbjastom Birminham; England, assignor; to Joseph: Lncas- .Limited;, Birmingham,England.-v

Application -July,15', 1949; Serial -No=-'4',=994 In.-Great;B ritainJuly-, 30tl948 lTCJai m This invention relates tdsystems forsupplyinmeans,- and the object of thepresent inventionds.

toenable this requirementto zbeemet in .a simple and satisfactory.manner.

The l invention comprises. the combination-of anelectromagnet. and.potentiometers having a rectifier-associated therewith;

In the accompanying drawings:

Figures 1 and 2 illustrate diagrammatically two embodiments of theinvention.

In one known system for supplying liquid fuel to a burner associatedwith a jet-propulsion engine, gas turbine, air heater or other analogousapparatus, a fluid operated servomechanism is employed for varying therate of supply of fuel to the burner. In the example shown in Figure 1,the pump comprises a pair of interengaging toothed rotors a adapted todraw liquid fuel from a supply tank as b and discharge it to a deliverypipe 0 leading to the burner. In this example a relief valve (1 isprovided by which fuel can be returned to the inlet side of the pump inthe event of excessive pressure being developed at the delivery side ofthe pump. The rate of flow to the pipe 0 is controlled automatically bya slidable throttle e having a conical or otherwise shaped end forvarying the effective area of an annular passage 1 leading to the pipe0. The throttle is movable by a fluid-operated servomechanism, whichcomprises a cylinder 9 and a piston h loaded by a spring 2', the pistonbeing formed on or secured to one end of the throttle 6. Liquid fuelfrom the pump can enter one end of the cylinder 9 by way of a passage7', and can be returned to a sump or the inlet side of the pump by wayof passages k, 121.. Also the ends of the cylinder are in communicationby way of a restricted orifice n which may be formed in the piston asshown, or may be provided in a branch passage interconnecting the endsof the cylinder. The discharge end of the passage It opens into aseating o with which co-operates a valve p. The arrangement is such thatwhen the. valve p is closed on to the seating o no fluid can flowthrough the cylinder 9. The fluid pressures acting on the opposite sidesof the piston h are then equal, and the spring i can move the pistonin;=. the. direction ;for restricting; the: area? of: the

passa e it. When: he-waive RJSRIILQVBCI; 011-: its;

seatin allowin fluid: o; fiowv throughi hee-nasasages; "b. 336;nrenonderating; fluid ressures i acting ononeiside ofitheuqistonhrmmlessthezlatter;

againstzthe;sprin wiirrthedireotionaior increasin the; areagof :thepassage: 1; sovfargthe apparatus. above-describe ;;is:oie known ,form:

In:.one1manne1;of applyin ;the-:presen-t invenap is; carried rby; the;plunger-sq: oigameleotltomag net havingzan excitinauvinding r;;tlieznluner:;bein loadecbbyempring s.-=. Therelectromagnetewindi es is energisedby current derived fronriaabatterwt, or other convenient"sourcetoi:directcurrent; ,and this current is supplied through a bridgecircuit having a pair of parallel branches It, ll formed in part by apair of potentiometers u, 21, provided with adjustable contacts y, :13,the latter being connected to opposite ends of the electro-magnetwinding, and the connection between one end of the solenoid winding andthe potentiometer 12 being efiected through a rectifier w permittingcurrent to flow in one direction only. The movable contact a: of thepotentiometer v is movable by hand or otherwise under the control of anattendant. The movable contact 1/ of the potentiometer u is movable bythe piston it through a rod z.

The arrangement is such that when the piston h is in equilibrium, thatis to say, when the forces acting on opposite sides of the piston areequal, the bridge circuit above mentioned is slightly out of balance,and sufliciept current fiows through the electromagnet winding r toretain the valve p slightly open. When the attendant actuates thecontact a: of the potentiometer v in one direction, current can flow tothe Winding 1' for opening the valve p to a greater extent. Theservo-mechanism is thereby set in motion, and the contact 1 of the otherpotentiometer u is thereby moved until the original state of the bridgecircuit is restored. When the attendant operates the movable contact wof the potentiometer v in the opposite direction no current will flow tothe solenoid as it is intercepted by the rectifier w. Consequently thevalve 10 will be closed by the spring 8, and the servo-mechanism will bemoved in the opposite direction until the original state of the bridgecircuit is restored.

Figure 2 illustrates an application of the invention to a system inwhich the liquid fuel is supplied by a variable delivery pump of theswash-plate type. The pump comprises a rotor 2 having bores 3 containingreciprocatory tion to theabove described apparatus;thezzvaivee plungers4 which co-operate with an angularly adjustable swash plate 5 in knownmanner. Fluid enters the pump along a passage 6 and is delivered by thepump along a passage 1. The swash-plate 5 is adjustable by a rod 8connected to the piston h of the servo-mechanism. In other respects thesystem illustrated by Figure 2 is similar to that illustrated by Figure1, and the above description of Figure 1 is applicable also to Figure 2.When the valve p is closed on to its seating, the piston It moves theswash plate 5 in the direction for increasing the pump output, and whenthe valve p is opened the piston It moves in the direction for reducingthe pump output.

In either of the systems above described it is not essential that thecontact :c shall be operable by or under the control of the attendant,as it may be actuated automatically in response to any predeterminedvariable condition. Thus it may be operable by a thermostatic device sothat the fuel supply is restricted when a predetermined temperature isexceeded. Further, instead of supplying current to the solenoid from abattery or other substantially constant source it may be supplied from athermo-c-ouple responsive to temperature changes, the contact a: beingthen adjusted to determine the temperature at which it is desired toeffect reduction of fuel supply.

By this invention the electrical control of the servo-mechanism forregulating the rate of fuel supply can be effected in a very simple andconvenient manner. Y

Having thus described my invention what I 4 claim as new and desire tosecure by Letters Patent is:

Fuel supply regulating means comprising in combination a valve, anelectromagnet having an exciting winding and a movable member responsiveto excitation of the winding for moving the valve in one direction, aspring opposing movement of the valve by the movable member of theelectromagnet, an electric current supply circuit having a pair ofparallel branches, a pair of potentiometers forming parts of the circuitbranches and having adjustable contacts connected to opposite ends ofthe electromagnet winding, a rectifier connected between one of thepotentiometer contacts and the corresponding end of the electromagnetwinding, a fuel regulating member, and a fluid-operated servo-mechanismoperable under the control of the valve for actuating the fuelregulating member and imparting adjusting movement to one of thepotentiometer contacts.

THOMAS ALFRED HARRIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,262,173 Fischer Nov. 11, 19412,390,425 Crum Dec. 4, 1945 2,403,371 Ifield July 2, 1946 2,403,917Gille July 16, 1946 2,498,654 Deakin Feb. 28, 1950

